package com.cybertron.am.wordpress.util;

/**
 * Created by xiezhouyan on 16-7-27.
 */

import org.apache.commons.collections4.map.ListOrderedMap;
import org.apache.commons.lang3.StringUtils;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

/**
 * Created by xiezhouyan on 16-1-8.
 */
public class UrlUtil {

    private static final int RADIX = 16;
    private static final byte ESCAPE_CHAR = '%';
    private static final byte PLUS_CHAR = '+';

    private UrlUtil() {

    }

    public static String trim(String url) {
        return url == null ? null : url.replaceAll(" ", "%20");
    }

    public static String urlEncode(String value) {
        return urlEncode(value, "UTF-8");
    }

    public static String urlEncode(String value, String enc) {
        try {
            value = URLEncoder.encode(value, enc);
        } catch (UnsupportedEncodingException ex) {
            throw new RuntimeException(ex);
        }
        return value;
    }

    /**
     * Decodes using URLDecoder - use when queries or form post values are decoded
     *
     * @param value value to decode
     * @param enc   encoding
     */
    public static String urlDecode(String value, String enc) {
        return urlDecode(value, enc, false);
    }

    private static String urlDecode(String value, String enc, boolean isPath) {

        boolean needDecode = false;
        int escapesCount = 0;
        int i = 0;
        while (i < value.length()) {
            char ch = value.charAt(i++);
            if (ch == ESCAPE_CHAR) {
                escapesCount += 1;
                i += 2;
                needDecode = true;
            } else if (!isPath && ch == PLUS_CHAR) {
                needDecode = true;
            }
        }
        if (needDecode) {
            byte[] valueBytes = null;
            try {
                valueBytes = value.getBytes(enc);
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException("url decode error", e);
            }
            ByteBuffer in = ByteBuffer.wrap(valueBytes);
            ByteBuffer out = ByteBuffer.allocate(in.capacity() - 2 * escapesCount);
            while (in.hasRemaining()) {
                final int b = in.get();
                if (!isPath && b == PLUS_CHAR) {
                    out.put((byte) ' ');
                } else if (b == ESCAPE_CHAR) {
                    try {
                        final int u = digit16((byte) in.get());
                        final int l = digit16((byte) in.get());
                        out.put((byte) ((u << 4) + l));
                    } catch (final ArrayIndexOutOfBoundsException e) {
                        throw new RuntimeException("Invalid URL encoding: ", e);
                    }
                } else {
                    out.put((byte) b);
                }
            }
            out.flip();
            return Charset.forName(enc).decode(out).toString();
        } else {
            return value;
        }
    }

    private static int digit16(final byte b) {
        final int i = Character.digit((char) b, RADIX);
        if (i == -1) {
            throw new RuntimeException("Invalid URL encoding: not a valid digit (radix " + RADIX + "): " + b);
        }
        return i;
    }


    public static String urlDecode(String value) {
        return urlDecode(value, "UTF-8");
    }

    /**
     * URL path segments may contain '+' symbols which should not be decoded into ' '
     * This method replaces '+' with %2B and delegates to URLDecoder
     *
     * @param value value to decode
     */
    public static String pathDecode(String value) {
        return urlDecode(value, "UTF-8", true);
    }


    /**
     * Create a map from String to String that represents the contents of the query
     * portion of a URL. For each x=y, x is the key and y is the value.
     *
     * @param s the query part of the URI.
     * @return the map.
     */
    public static Map<String, String> parseQueryString(String s) {
        Map<String, String> ht = new ListOrderedMap<String, String>();
        StringTokenizer st = new StringTokenizer(s, "&");
        while (st.hasMoreTokens()) {
            String pair = st.nextToken();
            int pos = pair.indexOf('=');
            if (pos == -1) {
                ht.put(pair, "");
            } else {
                ht.put(pair.substring(0, pos), urlDecode(pair.substring(pos + 1)));
            }
        }
        return ht;
    }

    /**
     * Return everything in the path up to the last slash in a URI.
     *
     * @param baseURI
     * @return the trailing
     */
    public static String getStem(String baseURI) {
        int idx = baseURI.lastIndexOf('/');
        String result = baseURI;
        if (idx != -1) {
            result = baseURI.substring(0, idx);
        }
        return result;
    }

    public static String resolveUrl(final String baseUrl, final String relativeUrl) {
        if (baseUrl == null) {
            throw new IllegalArgumentException("Base URL must not be null");
        }
        if (relativeUrl == null) {
            throw new IllegalArgumentException("Relative URL must not be null");
        }
        final Url url = resolveUrl(parseUrl(baseUrl.trim()), relativeUrl.trim());

        return url.toString();
    }

    public static String getHost(String url) {
        String host = url;
        int i = StringUtils.ordinalIndexOf(url, "/", 3);
        if (i > 0) {
            host = StringUtils.substring(url, 0, i);
        }
        return host;
    }

    private static Pattern patternForProtocal = Pattern.compile("[\\w]+://");

    public static String removeProtocol(String url) {
        return patternForProtocal.matcher(url).replaceAll("");
    }

    public static String getDomain(String url) {
        String domain = removeProtocol(url);
        int i = StringUtils.indexOf(domain, "/", 1);
        if (i > 0) {
            domain = StringUtils.substring(domain, 0, i);
        }
        return removePort(domain);
    }

    public static String removePort(String domain) {
        int portIndex = domain.indexOf(":");
        if (portIndex != -1) {
            return domain.substring(0, portIndex);
        } else {
            return domain;
        }
    }

    private static Url parseUrl(final String spec) {
        final Url url = new Url();
        int startIndex = 0;
        int endIndex = spec.length();

        // Section 2.4.1: Parsing the Fragment Identifier
        //
        // If the parse string contains a crosshatch "#" character, then the
        // substring after the first (left-most) crosshatch "#" and up to the
        // end of the parse string is the <fragment> identifier. If the
        // crosshatch is the last character, or no crosshatch is present, then
        // the fragment identifier is empty. The matched substring, including
        // the crosshatch character, is removed from the parse string before
        // continuing.
        //
        // Note that the fragment identifier is not considered part of the URL.
        // However, since it is often attached to the URL, parsers must be able
        // to recognize and set aside fragment identifiers as part of the
        // process.
        final int crosshatchIndex = indexOf(spec, '#', startIndex, endIndex);

        if (crosshatchIndex >= 0) {
            url.fragment_ = spec.substring(crosshatchIndex + 1, endIndex);
            endIndex = crosshatchIndex;
        }
        // Section 2.4.2: Parsing the Scheme
        //
        // If the parse string contains a colon ":" after the first character
        // and before any characters not allowed as part of a scheme name (i.e.,
        // any not an alphanumeric, plus "+", period ".", or hyphen "-"), the
        // <scheme> of the URL is the substring of characters up to but not
        // including the first colon. These characters and the colon are then
        // removed from the parse string before continuing.
        final int colonIndex = indexOf(spec, ':', startIndex, endIndex);

        if (colonIndex > 0) {
            final String scheme = spec.substring(startIndex, colonIndex);
            if (isValidScheme(scheme)) {
                url.scheme_ = scheme;
                startIndex = colonIndex + 1;
            }
        }
        // Section 2.4.3: Parsing the Network Location/Login
        //
        // If the parse string begins with a double-slash "//", then the
        // substring of characters after the double-slash and up to, but not
        // including, the next slash "/" character is the network location/login
        // (<net_loc>) of the URL. If no trailing slash "/" is present, the
        // entire remaining parse string is assigned to <net_loc>. The double-
        // slash and <net_loc> are removed from the parse string before
        // continuing.
        //
        // Note: We also accept a question mark "?" or a semicolon ";" character
        // as
        // delimiters for the network location/login (<net_loc>) of the URL.
        final int locationStartIndex;
        int locationEndIndex;

        if (spec.startsWith("//", startIndex)) {
            locationStartIndex = startIndex + 2;
            locationEndIndex = indexOf(spec, '/', locationStartIndex, endIndex);
            if (locationEndIndex >= 0) {
                startIndex = locationEndIndex;
            }
        } else {
            locationStartIndex = -1;
            locationEndIndex = -1;
        }
        // Section 2.4.4: Parsing the Query Information
        //
        // If the parse string contains a question mark "?" character, then the
        // substring after the first (left-most) question mark "?" and up to the
        // end of the parse string is the <query> information. If the question
        // mark is the last character, or no question mark is present, then the
        // query information is empty. The matched substring, including the
        // question mark character, is removed from the parse string before
        // continuing.
        final int questionMarkIndex = indexOf(spec, '?', startIndex, endIndex);

        if (questionMarkIndex >= 0) {
            if ((locationStartIndex >= 0) && (locationEndIndex < 0)) {
                // The substring of characters after the double-slash and up to,
                // but not
                // including, the question mark "?" character is the network
                // location/login
                // (<net_loc>) of the URL.
                locationEndIndex = questionMarkIndex;
                startIndex = questionMarkIndex;
            }
            url.query_ = spec.substring(questionMarkIndex + 1, endIndex);
            endIndex = questionMarkIndex;
        }
        // Section 2.4.5: Parsing the Parameters
        //
        // If the parse string contains a semicolon ";" character, then the
        // substring after the first (left-most) semicolon ";" and up to the end
        // of the parse string is the parameters (<params>). If the semicolon
        // is the last character, or no semicolon is present, then <params> is
        // empty. The matched substring, including the semicolon character, is
        // removed from the parse string before continuing.
        final int semicolonIndex = indexOf(spec, ';', startIndex, endIndex);

        if (semicolonIndex >= 0) {
            if ((locationStartIndex >= 0) && (locationEndIndex < 0)) {
                // The substring of characters after the double-slash and up to,
                // but not
                // including, the semicolon ";" character is the network
                // location/login
                // (<net_loc>) of the URL.
                locationEndIndex = semicolonIndex;
                startIndex = semicolonIndex;
            }
            url.parameters_ = spec.substring(semicolonIndex + 1, endIndex);
            endIndex = semicolonIndex;
        }
        // Section 2.4.6: Parsing the Path
        //
        // After the above steps, all that is left of the parse string is the
        // URL <path> and the slash "/" that may precede it. Even though the
        // initial slash is not part of the URL path, the parser must remember
        // whether or not it was present so that later processes can
        // differentiate between relative and absolute paths. Often this is
        // done by simply storing the preceding slash along with the path.
        if ((locationStartIndex >= 0) && (locationEndIndex < 0)) {
            // The entire remaining parse string is assigned to the network
            // location/login (<net_loc>) of the URL.
            locationEndIndex = endIndex;
        } else if (startIndex < endIndex) {
            url.path_ = spec.substring(startIndex, endIndex);
        }
        // Set the network location/login (<net_loc>) of the URL.
        if ((locationStartIndex >= 0) && (locationEndIndex >= 0)) {
            url.location_ = spec
                    .substring(locationStartIndex, locationEndIndex);
        }
        return url;
    }

    /*
     * Returns true if specified string is a valid scheme name.
     */
    private static boolean isValidScheme(final String scheme) {
        final int length = scheme.length();
        if (length < 1) {
            return false;
        }
        char c = scheme.charAt(0);
        if (!Character.isLetter(c)) {
            return false;
        }
        for (int i = 1; i < length; i++) {
            c = scheme.charAt(i);
            if (!Character.isLetterOrDigit(c) && (c != '.') && (c != '+')
                    && (c != '-')) {
                return false;
            }
        }
        return true;
    }

    private static Url resolveUrl(final Url baseUrl, final String relativeUrl) {
        final Url url = parseUrl(relativeUrl);
        // Step 1: The base URL is established according to the rules of
        // Section 3. If the base URL is the empty string (unknown),
        // the embedded URL is interpreted as an absolute URL and
        // we are done.
        if (baseUrl == null) {
            return url;
        }
        // Step 2: Both the base and embedded URLs are parsed into their
        // component parts as described in Section 2.4.
        // a) If the embedded URL is entirely empty, it inherits the
        // entire base URL (i.e., is set equal to the base URL)
        // and we are done.
        if (relativeUrl.length() == 0) {
            return new Url(baseUrl);
        }
        // b) If the embedded URL starts with a scheme name, it is
        // interpreted as an absolute URL and we are done.
        if (url.scheme_ != null) {
            return url;
        }
        // c) Otherwise, the embedded URL inherits the scheme of
        // the base URL.
        url.scheme_ = baseUrl.scheme_;
        // Step 3: If the embedded URL's <net_loc> is non-empty, we skip to
        // Step 7. Otherwise, the embedded URL inherits the <net_loc>
        // (if any) of the base URL.
        if (url.location_ != null) {
            return url;
        }
        url.location_ = baseUrl.location_;
        // Step 4: If the embedded URL path is preceded by a slash "/", the
        // path is not relative and we skip to Step 7.
        if ((url.path_ != null) && url.path_.startsWith("/")) {
            url.path_ = removeLeadingSlashPoints(url.path_);
            return url;
        }
        // Step 5: If the embedded URL path is empty (and not preceded by a
        // slash), then the embedded URL inherits the base URL path,
        // and
        if (url.path_ == null) {
            url.path_ = baseUrl.path_;
            // a) if the embedded URL's <params> is non-empty, we skip to
            // step 7; otherwise, it inherits the <params> of the base
            // URL (if any) and
            if (url.parameters_ != null) {
                return url;
            }
            url.parameters_ = baseUrl.parameters_;
            // b) if the embedded URL's <query> is non-empty, we skip to
            // step 7; otherwise, it inherits the <query> of the base
            // URL (if any) and we skip to step 7.
            if (url.query_ != null) {
                return url;
            }
            url.query_ = baseUrl.query_;
            return url;
        }
        // Step 6: The last segment of the base URL's path (anything
        // following the rightmost slash "/", or the entire path if no
        // slash is present) is removed and the embedded URL's path is
        // appended in its place. The following operations are
        // then applied, in order, to the new path:
        final String basePath = baseUrl.path_;
        String path = new String();

        if (basePath != null) {
            final int lastSlashIndex = basePath.lastIndexOf('/');

            if (lastSlashIndex >= 0) {
                path = basePath.substring(0, lastSlashIndex + 1);
            }
        } else {
            path = "/";
        }
        path = path.concat(url.path_);
        // a) All occurrences of "./", where "." is a complete path
        // segment, are removed.
        int pathSegmentIndex;

        while ((pathSegmentIndex = path.indexOf("/./")) >= 0) {
            path = path.substring(0, pathSegmentIndex + 1).concat(
                    path.substring(pathSegmentIndex + 3));
        }
        // b) If the path ends with "." as a complete path segment,
        // that "." is removed.
        if (path.endsWith("/.")) {
            path = path.substring(0, path.length() - 1);
        }
        // c) All occurrences of "<segment>/../", where <segment> is a
        // complete path segment not equal to "..", are removed.
        // Removal of these path segments is performed iteratively,
        // removing the leftmost matching pattern on each iteration,
        // until no matching pattern remains.
        while ((pathSegmentIndex = path.indexOf("/../")) > 0) {
            final String pathSegment = path.substring(0, pathSegmentIndex);
            final int slashIndex = pathSegment.lastIndexOf('/');

            if (slashIndex < 0) {
                continue;
            }
            if (!pathSegment.substring(slashIndex).equals("..")) {
                path = path.substring(0, slashIndex + 1).concat(
                        path.substring(pathSegmentIndex + 4));
            }
        }
        // d) If the path ends with "<segment>/..", where <segment> is a
        // complete path segment not equal to "..", that
        // "<segment>/.." is removed.
        if (path.endsWith("/..")) {
            final String pathSegment = path.substring(0, path.length() - 3);
            final int slashIndex = pathSegment.lastIndexOf('/');

            if (slashIndex >= 0) {
                path = path.substring(0, slashIndex + 1);
            }
        }

        path = removeLeadingSlashPoints(path);

        url.path_ = path;
        // Step 7: The resulting URL components, including any inherited from
        // the base URL, are recombined to give the absolute form of
        // the embedded URL.
        return url;
    }

    private static String removeLeadingSlashPoints(String path) {
        while (path.startsWith("/..")) {
            path = path.substring(3);
        }

        return path;
    }

    /**
     * Code copied from HtmlUnit
     * (src/main/java/com/gargoylesoftware/htmlunit/TextUtil.java)
     * (https://htmlunit.svn.sourceforge.net/svnroot/htmlunit/trunk/htmlunit -
     * commit 5556)
     */
    public static boolean startsWithIgnoreCase(final String stringToCheck,
                                               final String prefix) {

        if (prefix.length() == 0) {
            throw new IllegalArgumentException("Prefix may not be empty");
        }

        final int prefixLength = prefix.length();
        if (stringToCheck.length() < prefixLength) {
            return false;
        }
        return stringToCheck.substring(0, prefixLength).toLowerCase()
                .equals(prefix.toLowerCase());
    }

    /**
     * Code copied from HtmlUnit
     * (src/main/java/com/gargoylesoftware/htmlunit/StringUtils.java)
     * (https://htmlunit.svn.sourceforge.net/svnroot/htmlunit/trunk/htmlunit -
     * commit 5556)
     */
    public static int indexOf(final String s, final char searchChar,
                              final int beginIndex, final int endIndex) {
        for (int i = beginIndex; i < endIndex; i++) {
            if (s.charAt(i) == searchChar) {
                return i;
            }
        }
        return -1;
    }


    public static String encodeFormParams(Map<String, String> params) {
        return params.entrySet()
                .stream()
                .filter(entity -> entity.getValue() != null)
                .map(item -> String.format("%s=%s", item.getKey(), urlDecode(item.getValue())))
                .collect(Collectors.joining("&"));
    }

    private static class Url {

        private String scheme_;
        private String location_;
        private String path_;
        private String parameters_;
        private String query_;
        private String fragment_;

        public Url(final Url url) {
            scheme_ = url.scheme_;
            location_ = url.location_;
            path_ = url.path_;
            parameters_ = url.parameters_;
            query_ = url.query_;
            fragment_ = url.fragment_;
        }

        public Url() {
        }

        @Override
        public String toString() {
            final StringBuilder sb = new StringBuilder();

            if (scheme_ != null) {
                sb.append(scheme_);
                sb.append(':');
            }
            if (location_ != null) {
                sb.append("//");
                sb.append(location_);
            }
            if (path_ != null) {
                sb.append(path_);
            }
            if (parameters_ != null) {
                sb.append(';');
                sb.append(parameters_);
            }
            if (query_ != null) {
                sb.append('?');
                sb.append(query_);
            }
            if (fragment_ != null) {
                sb.append('#');
                sb.append(fragment_);
            }
            return sb.toString();
        }
    }
}
